Summary Influenza virus vaccines are widely used. It is known that there are differences in the breadth and duration of protection between inactivated (IIV) and live attenuated influenza virus (LAIV) vaccines with the latter inducing broader and longer lasting protection. However, it is unclear which factors are causing these differences. Here we aim to characterize the LAIV induced antibody response in peripheral blood and mucosal fluids to conserved epitopes on the viral hemagglutinin and neuraminidase. We hypothesize that induction of antibodies to conserved sites contributes to the better protection observed with LAIV. To investigate this, we will interrogate a unique set of samples from clinical trials performed with LAIV over two seasons in The Gambia. Data from this study will help us to better understand the mechanism of broad protection of LAIV and it will allow to gauge the potential of using LAIV as prime for subsequent boosts with hemagglutinin-stalk and/or neuraminidase based universal influenza virus vaccines.